GB2403955A

GB2403955A - Organic thin film manufacturing method and apparatus

Info

Publication number: GB2403955A
Application number: GB0403645A
Authority: GB
Inventors: Noriyuki Matsukaze; Hiroshi Kimura
Original assignee: Fuji Electric Holdings Ltd
Current assignee: Fuji Electric Co Ltd
Priority date: 2003-07-17
Filing date: 2004-02-19
Publication date: 2005-01-19
Anticipated expiration: 2024-02-19
Also published as: JP2005036296A; KR100826743B1; GB2403955B; US20050011443A1; TW200505280A; GB0403645D0; JP4013859B2; KR20050010470A

Abstract

An organic thin film manufacturing method and apparatus, characterised by feeding an organic material in a vapour state into a vapour deposition apparatus installed in a vacuum chamber 10 from a material introducing part 20 installed outside the vapour deposition apparatus, thus forming a thin film of the organic material on at least one substrate disposed inside the vapour deposition apparatus, wherein the material introducing part has a structure such that the pressure thereinside can be set independently of that inside the vapour deposition apparatus, and has an exhauster 13b independent to that of the vapour deposition apparatus. An organic electroluminescent device (organic EL device) can be formed using said method/apparatus. A first electrode is formed on a substrate followed by an organic layer and finally a second electrode.

Description

Organic Thin Film Manufacturing Method and Manufacturing Apparatus The

present invention relates to an organic thin film manufacturing method and manufacturing apparatus. More specifically, the present invention relates to an organic thin film manufacturing method and manufacturing apparatus useful in the manufacture of organic EL devices.

The following prior art documents are referred to herein: Patent Document 1 - Japanese Patent Application Laid-open No. 2003-7464 Patent Document 2 - Japanese Patent Application Laid-open No. 2001 Patent Document 3 Published Japanese Translation of PCT Application No. 2001 -523768 Non-Patent Document 1 - C.W. Tang and S.A. Van Slyke, Appl. Phys. Left., 51, 913 (1987) In recent years, there have been rapid advances in increasing the speed of, and expanding the range of application of, information communication. Amid this, high-detail display devices having low power consumption and fast response that are able to answer to the requirements on display devices with regard to portability, displaying moving pictures and so on have been devised. In particular, with organic electroluminescent devices (hereinafter referred to as 'organic EL devices'), since the announcement of a high-efficiency organic EL device having a two-layer laminated structure by C.W. Tang of Eastman Kodak in 1987 (see Non-Patent Document 1), up to the present, various organic EL devices have been developed, and some have started to be put to practical use.

A method in which vapour deposition is carried out with heating has been used as the method of forming the organic compound thin films used as the light-emitting part (hereinafter referred to as the 'organic EL layer') of an organic EL device. In this method, in general an indirect heating method is adopted in which a material for the thin film is housed in a vessel such as a boat or a crucible, and heating is carried out from the outside using a heater or the like. When forming an organic EL layer, it is desirable for the fluctuation in the film thickness to be kept down to within + 5% from the central value over the area of film formation. In response to this demand, improvements in large-area film formation technology have been made through a method in which an evaporation source close to a point evaporation source or an evaporation source called a line source is used.

To reduce the cost of organic EL devices, it is considered to be indispensable to improve the efficiency of utilization of the organic EL layer materials. The current state of affairs is that if a point evaporation source is used, then most of the vapour stream from the material becomes attached to the side walls of the apparatus, and very little is deposited onto the substrate on which the film is being formed; the efficiency of utilization of the material is thus very low. A method has thus been developed in which a line- shaped evaporation source called a line source is used, and the distance between the substrate on which the film is being formed and the evaporation source is reduced, whereby there is little fluctuation in the film thickness in the longitudinal direction, and moreover the method is excellent in terms of the efficiency of utilization of the material and the ability to increase the area over which the film is formed (see Patent Document 1).

Figure 5 shows a schematic view of the conventionally proposed vapour deposition apparatus that uses a line source. The apparatus has, inside a vacuum chamber 50 that is communicated to an exhauster 53, a line source 51 containing a heating boat 59 in which an organic material 56 is housed, and a substrate is disposed facing the line source 51. The heating boat 59 has a heater built therein, and is connected to a heater power source 54.

The organic material 56 is evaporated by heating using the heater, and thus becomes a vapour stream 55, and hence is deposited on the surface of the substrate. The deposition of the organic material on the surface of the substrate may be monitored by a film thickness measuring instrument 58 connected to a film thickness measuring sensor 57. Moreover, an attachment-preventing plate 52 for preventing deposition of the organic material on the side walls may also be provided.

With most evaporation sources of the line source or point evaporation source type, a method is adopted in which the material is filled into a heating boat, a crucible or the like or onto the base thereof. However, regarding the organic material to be subjected to the vapour deposition, depending on the nature thereof, some are materials that sublime, and others are materials that evaporate after melting. In the case of a subliming material in particular, that part of the material in contact with the heated walls evaporates preferentially, and hence fluctuations arise in the film thickness. A method has thus been proposed in which the vapour deposition is carried out while vibrating the evaporation source itself. In recent years, an organic material vapour deposition method in which the organic material is housed in a crucible mixed with a powder or pulverized material of a ceramic, a metal or the like, and the crucible is heated has been proposed (see Patent Document 2). According to this method, the transmission of heat within the vessel can be improved, and hence improvements can be made with regard to the vapour deposition rate dropping or the sublimation efficiency dropping, regardless of the amount consumed of the material.

Moreover, a method and apparatus for forming a thin film of an organic material smoothly and uniformly using a low-pressure organic vapour deposition or low-pressure organic molecular beam vapour deposition method have been proposed (see Patent Document 3). In this document, a method is disclosed in which the organic molecules to be subjected to vapour deposition are led to the substrate using a carrier gas from an independent evaporation source, but there is no disclosure regarding the evaporation source and the film formation chamber having independent exhaust systems.

In the case of using a conventional type line source or point evaporation source type evaporation source, it is necessary to open the vacuum chamber every time the organic material being subjected to the vapour deposition is filled in, and even if the vacuum is not released, it is necessary to carry out pretreatment in which the material is heated immediately after the filling to drive out gases and moisture that have got into the material during storage. Moreover, the optimum heating conditions differ between materials that sublime and materials that evaporate after melting, and hence there is a risk of the control of the material heating method becoming complicated.

Moreover, the various organic materials used in an organic EL device each have their own temperature-vapour pressure characteristic. In general, regarding the temperature-vapour pressure characteristic of a subliming material, the temperature range for obtaining a prescribed vapour stream is very narrow, i.e. there is high sensitivity to temperature. Temperature control is thus very important to vapour-depositing such an organic material uniformly over a large area. However, the larger the evaporation source, the larger the thermal capacity, and hence a long time is required for soaking, and temperature control becomes very difficult. Moreover, as the evaporation source is made larger, the number of things that need to be considered with regard to the method of loading the material into the heating boat 59 increases. For example, if a large amount of the material is consumed during mass production, then the surface of the evaporating material will drop down within the evaporation source, which may give rise to changes in the film thickness and the vapour deposition rate.

Furthermore, to obtain little fluctuation in the film thickness in the longitudinal direction when using a line source 51 as shown in Figure 5, it is necessary to make the loading of the material into the heating boat 59 uniform, and it is thought that the reproducibility and stability of the film thickness will depend on the loading method.

The problem to be solved by the present invention is to provide a line source for which the various problems described above that arise during mass production are resolved, and vapour deposition over a large area is possible.

An organic thin film manufacturing method according to a first embodiment of the present invention is characterised by comprising a step of feeding an organic material in a vapour state into a line source of a vapour deposition apparatus that has a line source and is installed in a vacuum chamber from a material introducing part installed outside the vapour deposition apparatus, thus forming a thin film of the organic material on at least one substrate disposed inside the vapour deposition apparatus, wherein the material introducing part has a structure such that the pressure thereinside can be set independently of that inside the vapour deposition apparatus, and has an exhauster independent to that of the vapour deposition apparatus.

An organic thin film manufacturing apparatus according to a second embodiment of the present invention is characterised by comprising a vapour deposition apparatus that has a line source and is installed in a vacuum chamber, and a material introducing part that is installed outside the vapour deposition apparatus, has a structure such that the pressure thereinside can be set independently of that inside the vapour deposition apparatus, and is connected to an exhauster independent to that of the vapour deposition apparatus, wherein a vapour-state organic material is fed into the line source of the vapour deposition apparatus from the material introducing part, thus forming a thin film of the organic material on at least one substrate disposed inside the vapour deposition apparatus. This manufacturing apparatus is useful as an apparatus for manufacturing the organic EL layer of organic EL devices.

An organic EL device manufacturing method according to a third embodiment of the present invention is characterised by comprising a step of forming a first electrode on at least one substrate, a step of forming an organic EL layer on the first electrode, and a step of forming a second electrode on the organic EL layer, wherein the step of forming the organic EL layer comprises feeding an organic material in a vapour state into a line source of a vapour deposition apparatus that has a line source and is installed in a vacuum chamber from a material introducing part installed outside the vapour deposition apparatus, thus forming a thin film of the organic material on the at least one substrate which is disposed inside the vapour deposition apparatus, wherein the material introducing part has a structure such that the pressure thereinside can be set independently of that inside the vapour deposition apparatus, and has an exhauster independent to that of the vapour deposition apparatus.

An organic EL device manufacturing apparatus according to a fourth embodiment of the present invention is characterised by comprising means for forming a first electrode, means for forming an organic EL layer, and means for forming a second electrode, wherein the means for forming an organic EL layer comprises a vapour deposition apparatus that has a line source and is installed in a vacuum chamber, and a material introducing part that is installed outside the vapour deposition apparatus, has a structure such that the pressure thereinside can be set independently of that inside the vapour deposition apparatus, and is connected to an exhauster independent to that of the vapour deposition apparatus, and wherein a vapour-state organic material is fed into the line source of the vapour deposition apparatus from the material introducing part, thus forming a thin film of the organic material on at least one substrate disposed inside the vapour deposition apparatus.

In the first to fourth embodiments described above, the material introducing part may have a crucible for holding the organic material, crucible fixing means for holding the crucible, and heating means for heating the crucible, with the organic material being vaporized by heating the crucible using the heating means. Furthermore, there may be a blocking plate for dispersing the vapour-state organic material that has been fed into the vacuum chamber, with the blocking plate being temperature-regulated so as to prevent attachment of the organic material onto the blocking plate.

Advantages of adopting such a constitution include: À Because the material introducing part is independent, and the filling of the material is carried out outside the apparatus, it is not necessary to open the vacuum chamber to the atmosphere.

À Because the material introducing part is independent, and the organic material is fed in as a vapour, the line source can be designed with no consideration being given to whether the organic material sublimes or melts.

À Because the material is fed in as a vapour, it is not necessary to give consideration to the effects of the evaporation plane of the material, and even if the apparatus is used many times during mass production, there is little fluctuation in the film thickness or the film formation rate, and hence control is easy.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic sectional view showing a vapour deposition apparatus of the present invention; Figure 2 is a schematic sectional view showing a material introducing part of the vapour deposition apparatus of the present invention; Figure 3 is a schematic top view showing an example of a blocking plate of the vapour deposition apparatus of the present invention; Figure 4 is a schematic top view showing an example of a gas distributing pipe of the vapour deposition apparatus of the present invention; and Figure 5 is a schematic sectional view showing an example of a vapour deposition apparatus using a line source according to prior art.

An example of an organic thin film manufacturing apparatus of the present invention is shown in Figure 1. In the apparatus of the present invention, a vacuum chamber 10 and a material introducing part 20 are separated from one another by a valve 21 provided in a joint part 27, and hence form independent vacuum systems. The vacuum chamber 10 and the material introducing part 20 are thus communicated respectively to independent exhausters 1 3a and 1 3b. The vacuum chamber 10 contains a line source 11, and a substrate disposed so as to face the line source 11. It is also possible to provide a substrate holder (not shown) that is able to hold a plurality of substrates in the vacuum chamber 10, and thus carry out film formation on a plurality of substrates simultaneously. The line source 11 contains a gas distributing pipe 23 that is communicated to the material introducing part 20 via the joint part 27, and a blocking plate 19 that is positioned between the gas distributing pipe 23 and the substrate. The gas distributing pipe 23 and the blocking plate 19 each contain heating means (not shown) for preventing attachment of the organic material, and these heating means are connected to a heater power source 14. A film thickness measuring sensor 17 may be provided in the vacuum chamber 10, with this film thickness measuring sensor 17 being connected to a film thickness measuring instrument 18, whereby the formation of the organic thin film can be carried out while checking on the state of film formation on the substrate.

Furthermore, an attachment-preventing plate 12 may be provided on the side walls inside the vacuum chamber 10. It is preferable to further provide heating means (not shown) in the attachment-preventing plate 12, thus preventing attachment of the organic material thereon.

With the line source 11 of the present invention, the organic material is not filled into a crucible provided at the bottom of the line source, but rather the organic material is fed in a vapour state into the gas distributing pipe 23 inside the line source 11 from the material introducing part 20, which is provided below the line source 11 outside the vacuum chamber 10, via the joint part 27. The line source 1 1 has a length greater than that of the region of the substrate over which film formation is to be carried out. The desired vapour deposition can be carried out through the substrate passing over the line source 1 1, or the line source 1 1 passing under the substrate. The blocking plate 19 provided inside the line source 1 1 has a large number of holes formed therein such that the vapour stream from below becomes uniform within the source. It is preferable to provide heating means (not shown) such as a heater in the line source 1 1, thus heating the line source 11 and hence preventing deposition of the vapour-state organic material.

The blocking plate 19 is a structure for distributing the vapour of the organic material, which is fed from the gas distributing pipe 23 provided therebelow, uniformly over the whole of the substrate provided thereabove.

The blocking plate 19 should be a plate, structure or the like able to block and distribute the vapour. There are no particular limitations on the shape and size thereof, with it being possible to adopt a suitable shape and size as required. Figure 3 shows a top view of an example of a blocking plate 19 that can be used in the present invention. With the structure of Figure 3, there are a large number of stream-regulating holes 31 distributed over the whole of the blocking plate 19. The shape, size and distribution of the stream- regulating holes 31 can be set as appropriate. Moreover, there are no particular limitations on the material of the blocking plate 19, although this material must be one that will not react with or bind to the organic material that is used as the raw material, for example a metal such as Cu. To or Mo, an alloy such as SUS, or a ceramic such as alumina, zirconia or aluminium nitride. A material having a good thermal conductivity such as Cu or Mo is preferable. Furthermore, it is preferable to provide heating means (not shown) such as a heater in the blocking plate 19, and connect this heating means to the heater power source 14, thus heating the blocking plate 19, and hence preventing deposition of the vapour- state organic material.

The gas distributing pipe 23 is connected to the joint part 27, and is a structure for distributing the vapour-state organic material fed in via the joint part 27 uniformly throughout the whole of the line source 11. The gas distributing pipe 23 should be, for example, a structure such as a pipe able to distribute a vapour. There are no particular limitations on the shape and size of the gas distributing pipe 23, with it being possible to adopt a suitable shape and size as required. Figure 4 shows a top view of an example of a gas distributing pipe 23 that can be used in the present invention. With the structure of Figure 4, the gas distributing pipe 23 has a plurality of right-angled parts, and has a large number of stream-regulating holes 31 along the whole of the length thereof. The shape, size and distribution of the stream- regulating holes 31 can be set as appropriate. Moreover, there are no particular limitations on the material of the gas distributing pipe 23, although this material must be one that will not react with or bind to the organic material that is used as the raw material, for example a metal such as Cu. To or Mo, an alloy such as SUS, or a ceramic such as alumina, zirconia or aluminium nitride. A material having a good thermal conductivity such as Cu or Mo is preferable. Furthermore, it is preferable to provide heating means (not shown) such as a heater in the gas distributing pipe 23, and connect this heating means to the heater power source 14, thus heating the gas distributing pipe 23, and hence preventing deposition of the vapour-state organic material.

Figure 2 is a schematic sectional view showing an example of the material introducing part 20 used in the apparatus of the present invention.

The material introducing part 20 has a crucible 25 housing the organic material 24, with the crucible 25 being held by freely chosen fixing means, preferably so as to directly face the joint part 27. Furthermore, heating means such as a heater 22 that is connected to a heater power source 26 is 1 1 provided around the crucible 25, and the organic material 24 in the crucible is sublimed or else melted and then evaporated by the heating means to turn the organic material into a vapour, which is introduced into the vacuum chamber 10. Moreover, a heater (not shown) may also be provided on the side walls of the material introducing part 20, with this heater being connected to a heater power source 26, whereby the side walls can be heated, thus preventing attachment of the vapour-state organic material thereon.

Alternatively, it is also possible to adopt a form in which a gas introducing port (not shown) is further provided in the material introducing part 20, and an inert gas such as N2 or Ar is introduced into the material introducing part 20 as a carrier gas, whereby the vapourstate organic material evaporated in the crucible 25 is introduced into the vacuum chamber 10.

With the apparatus of the present invention, by closing the valve 21 provided in the joint part 27, it is possible to change the pressure in the material introducing part 20 independently of that in the vacuum chamber 10. That is, it is possible to fill the organic material 24 into the crucible 25 with only the material introducing part 20 open to atmospheric pressure.

An organic thin film manufacturing method of the present invention comprises heating and thus evaporating the organic material housed in the crucible 25 in the material introducing part 20, introducing the evaporated vapour-state organic material into the gas distributing pipe 23 in the line source 11 via the joint part 27 and distributing the vapour-state organic material through the line source 11, further introducing the vapour-state organic material into the vacuum chamber 10 via the blocking plate 19, and finally depositing the organic material onto the substrate on which film formation is to be carried out.

In this way, the organic material that has been vaporized in the material introducing part 20 outside the vacuum chamber 10 can be introduced into the vacuum chamber 10 (i.e. into the line source 1 1), and hence the line source 11 can be designed with no consideration being given to whether the organic material 24 is a subliming material or a material that evaporates after melting. Moreover, because the organic material is fed into the vacuum chamber 10 in a vapour state, it is not necessary to give consideration to the effects of changes in the evaporation plane of the material when designing the line source 11, and even if the apparatus is used many times during mass production, there will be little fluctuation in the film thickness distribution or the film formation rate, and hence control during film formation becomes easy. Moreover, as described above, when refilling with the organic material after the organic material has been consumed through evaporation, the filling of the organic material can be carried out while opening only the material introducing part 20 to the atmosphere, i.e. without exposing the whole of the vacuum chamber 10 to the atmosphere.

Moreover, pretreatment involving heating to drive out gases and moisture contained in the organic material can be carried out with the valve 21 closed. With the method of the present invention. the pretreatment can thus be carried out in a smaller space, and hence loss of the material during this stage can be minimized.

There are no particular limitations on the organic material used as the raw material so long as this organic material is a material from which a film can be formed using the vapour phase deposition method; it is possible to use any of various organic materials. For example, the following can be used as the organic material in the present invention: a chain polymer such as polyacetylene or a poly-yne; an electronically conjugated organic semiconductor material such as molecular crystals of a metal chelate compound (copper phthalocyanine etc.) or a polyacene (anthracene etc.); a charge transfer complex constituted from a compound that acts as a donor such as a nthracene, a diethyla mine, p-phenylenedia mine, tetramethyl-p-phenylendiamine (TMPD) or tetrathiofulvalene (TTF), and a compound that acts as an acceptor such as tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE) or p-chloranil; a colorant material; a fluorescent material; a liquid crystal material; etc. When carrying out film formation onto the substrate, it is preferable to set the pressure in the vacuum chamber 10 and the material introducing part to a pressure in a range of 10 Pa to 10-7 Pa, and then set the temperature of the side walls of the material introducing part 20, the joint part 27, the gas distributing pipe 23, the blocking plate 19 and the attachment-preventing plate 12 to a temperature higher than the set temperature of the vacuum chamber 10, thus preventing attachment and recrystallization of the organic material on these parts. Furthermore, the side walls of the material introducing part 20, the joint part 27, the gas distributing pipe 23, the blocking plate 19 and the attachment-preventing plate 12 are each heated by an independent heater, and hence the optimum temperature can be set for each of these parts separately, and moreover the time taken for each of these parts to reach the prescribed temperature can be shortened.

Moreover, it is preferable to suitably control the temperature distributions of the gas distributing pipe 23 and the blocking plate 19, which affect the film thickness distribution of the organic thin film formed by depositing the organic material. The whole of each of the gas distributing pipe 23 and the blocking plate 19 may be set to a uniform temperature of 380 to 400 C. Alternatively, the gas distributing pipe 23 and the blocking plate 19 may each have a set of a plurality of independently controlled heaters, with a suitable temperature distribution being attained by separately controlling each of the plurality of heaters.

Next, the valve 21 is opened, and the crucible 25 is heated to approximately 150 to 500 C in general, preferably 200 to 400 C, thus evaporating the organic material 24. In the case of using a conventional line source, the amount of the organic material charged in is large, and hence the thermal capacity of the line source as a whole (in particular inside the heating boat) is large, and thus the time required for the line source to reach and stabilize at the prescribed temperature has been long. However, with the method of the present invention, recharging of the organic material is easy, and moreover attachment of the organic material on parts other than the substrate can be prevented, and hence the amount of the organic material charged in for use in one film formation can be reduced, and thus the thermal capacity can be reduced, and hence the prescribed temperature can be reached in a relatively short time.

The organic thin film manufacturing method and manufacturing apparatus described above can be used in the manufacture of an organic EL device. Such an organic EL device has a structure comprising at least a first electrode, an organic EL layer and second electrode on a supporting substrate.

As the supporting substrate, an insulating substrate made of glass, plastic or the like, a substrate obtained by forming a thin insulating film on a semi-conductive or conductive substrate, a flexible film made from a polyolefin, an acrylic resin, a polyester resin, a polyimide resin or the like, and so on can be used.

The first electrode and the second electrode can each be used as either an anode that injects holes into the organic EL layer or a cathode that injects electrons into the organic EL layer. So that the injection of holes can be carried out efficiently, the anode is preferably formed usinga material having a high work function such as a transparent electrically conductive metal oxide such as ITO or IZO. In the case that a reflective anode is desired, a layered structure between such a transparent electrically conductive metal oxide and a reflective metal or alloy (a metal such as Al, Ag, Mo or W or an alloy thereof, an amorphous metal or alloy such as NiP, NiB, CrP or CrB, or a microcrystalline alloy such as NiAI) can be used for the anode.

Moreover, if necessary, the surface of the transparent electrically conductive metal oxide may be treated using UV, a plasma or the like, thus improving the ability to inject holes into the organic EL layer. For the cathode, a material having a low work function such as an electroninjecting metal such as an alkali metal, an alkaline earth metal or aluminium, or an alloy thereof is preferable. To obtain good film formation ability and low resistivity, it is preferable to use an aluminium alloy (in particular, an alloy with an alkali metal or an alkaline earth metal), an AgMg alloy or the like. Alternatively, in the case that it is desirable for the cathode to be transparent, a laminate of an ultra-thin film (thickness not more than 10 nm) of an electroninjecting metal or an alloy thereof as described above and a transparent electrically conductive oxide can be used for the cathode. The first electrode and the second electrode can be formed using a method known in the technical field in question such as vapour deposition, sputtering, CVD or laser ablation.

In the case that an organic EL device in which light-emitting parts that can be controlled independently of one another are arranged in a matrix shape is required, a passive matrix driving type device may be formed in which the first electrode and the second electrode 50 are each formed from a plurality of partial electrodes in a line pattern, with the partial electrodes of the first electrode and the partial electrodes of the second electrode running in orthogonal directions, and parts where partial electrodes to which a voltage is applied intersect one another emit light. Alternatively, a so-called active matrix driving type device may be formed in which switching devices (TFTs etc.) are formed on the substrate in one-to-one correspondence with the light-emitting parts, and are connected to the first electrode, which is constituted from a plurality of partial electrodes that are made to be in one- to-one correspondence with the switching devices, and this is combined with the second electrode which is formed integrally with the organic EL layer on the organic EL layer.

With the organic EL device of the present invention, the light may be extracted from the substrate side (the first electrode side), or from the second electrode side. The direction from which the light is extracted can be controlled by making one of the first electrode and the second electrode be reflective, and making the other be transparent.

The organic EL layer is a layer that receives injected holes and electrons, and emits light from the near ultraviolet region to visible region, preferably light in the blue to blue/green region. An organic EL layer that emits white light may also be used. When forming the organic EL device of the present invention, it is preferable to form each of the layers constituting the organic EL layer using the manufacturing method and manufacturing apparatus of the present invention. The organic EL layer has a structure comprising at least an organic light-emitting layer, and if necessary a hole injection layer, a hole transport layer, an electron transport layer, and/or an electron injection layer are interposed. Specifically, an organic EL layer having a layer structure such as the following is adopted.

(1) Organic light-emitting layer (2) Hole injection layer / organic light-emitting layer (3) Organic light-emitting layer / electron injection layer (4) Hole injection layer / organic light-emitting layer / electron injection layer (5) Hole injection layer / hole transport layer / organic light-emitting layer / electron injection layer (6) Hole injection layer / hole transport layer / organic light-emitting layer! electron transport layer / electron injection layer (In the above, the first electrode is connected to the organic light- emitting layer or the hole injection layer, and the second electrode is connected to the organic light-emitting layer or the electron injection layer.) Publicly known materials are used as the materials of the above- mentioned layers. To obtain luminescence from blue to blue/green in colour, for example a fluorescent whitening agent of benzothiazole type, benzimidazole type, benzoxazole type or the like, a metal chelated oxonium compound, a styrylbenzene type compound, an aromatic dimethylidene type compound, or the like is preferably used in the organic light-emitting layer. Alternatively, an organic light-emitting layer that emits light in any of various wavelength regions including white light may be formed by adding a dopant to a host compound. As the host compound, a distyrylarylene type compound, N,Nt-ditolyl-N,Nt-diphenyl-biphenylamine (TPD), aluminium tris- (8quinolinolate) (Alq3), or the like can be used. As the dopant, perylene (blue/purple), Coumarin 6 (blue), a quinacridone compound (blue/green to green), rubrene (yellow), 4-dicyanomethylene-2-(p-dimethylaminostyryl)-6methyl-4H-pyran (DCM, red), a platinum octoethylporphyrin complex (PtOEP, red), or the like can be used.

As the electron injection layer, a thin film (thickness not more than 10 nm) of an electron-injecting material such as an alkali metal, an alkaline earth metal, or an alloy containing an alkali metal or an alkaline earth metal, or an alkali metal fluoride may be used. Alternatively, an aluminium quinolinol complex doped with an alkali metal or an alkaline earth metal may be used. As the material of the electron transport layer, an oxodiazole derivative such as 2-(4-biphenyl)-5-(p-tbutylphenyl)-1,3,4-oxodiazole (PBD), a triazole derivative, a triazine derivative, a phenylquinoxaline, an aluminium quinolinol complex (e.g. Alq3), or the like can be used.

As the material of the hole transport layer, a publicly known material such as a triarylamine type material such as TED, N,N'-bis(l-naphthyl)-N, N'- diphenyl-biphenylamine (a-NPD) or 4,4t,4-tris(N-3-tolyl-Nphenylamino)triphenylamine (m-MTDATA) can be used. As the material of the hole injection layer, a phthalocyanine (copper phthalocyanine etc.), an indanthrene compound, or the like can be used.

An organic EL device that emits light of desired hues may also be formed by further providing colour filter layers and/or colour-converting layers on the organic EL device described above. Colour filter layers are layers that transmit only light in a specific wavelength region out of the light emitted from the organic EL layer. Colour-converting layers are layers that carry out so-called wavelength distribution conversion, absorbing a specific wavelength region component of the light emitted from the organic EL layer and emitting light in a different wavelength region. For example, red colour- converting layers that absorb a component from blue to blue/green in colour and emit red light may be provided. The colour purity of the emitted light may also be improved by using a combination of a colour- converting layer and a colour filter layer. Furthermore, in the case of using an organic EL device having a plurality of independently controlled light-emitting parts, by combining a plurality of types of colour filter layers and/or colour-converting layers, a multi-colour display can be formed. The colour-converting layers and colour filter layers can be formed from any chosen material known in the

technical field in question.

Following is a more concrete description of the present invention through examples; however, it goes without saying that the present invention is not limited by these examples, with it being possible to make various changes within a scope such that the gist of the present invention is not deviated from.

Example 1

Using the film manufacturing apparatus shown in Figure 1, a verificatory test was carried out into the stability of the film formation rate. Glass substrates each having dimensions of 50 mm x 50 mm were arranged in 15 rows by 3 columns in a substrate holder having a mounting region of dimensions 770 mm x 150 mm inside the vacuum chamber 10, which had an internal volume of 0.2 ma. The blocking plate 19 had dimensions of 800 mm x mm, and had circular stream-regulating holes of diameter 3 mm distributed uniformly over the whole thereof, with the aperture ratio (total area of stream-regulating holes / total area of blocking plate) being 0.5%.

The distance between the blocking plate 19 and the substrates was made to be 150 mm. Moreover, a crucible 25 having a bore diameter of 50 mm and a depth of 100 mm was provided in the material introducing part 20, which had an internal volume of 0.05 ma, and 100 g of aluminium tris-(8 quinolinolate) (Alq3) was charged into the crucible 25. Aiq3 is a material that is commonly used as an electron-transporting material in organic EL devices, and is known to sublime. The vacuum chamber 10 and the material introducing part 20 were connected together by the joint part 27, which was an SUS pipe of internal diameter 20 mm, and the tip of this pipe was connected to the gas distributing pipe 23, which had an internal diameter of 4 mm and had circular stream-regulating holes of diameter 2 mm distributed uniformly thereover.

Using the above apparatus, the target film formation rate was set to 10 nm/sec, and a verificatory investigation was carried out into the controllability and the temperature rising process. Regarding the heaters for the blocking plate, the joint part, and the side walls of the material introducing part, the target temperature was set to 400 C. The pressure in the vacuum chamber 10 and the material introducing part 20 was reduced down to 10-5 Pa, and then the power sources for all of the heaters were turned on simultaneously.

After the power sources had been turned on and the temperature of each of the parts had stabilized, the power source was turned on for the heater of the crucible, which was set to a target temperature of 320 C. The Aiq3 was thus heated, and 2 hours was required for the rate of the film formation onto the substrates to reach 10 nm/sec. During the experimental sequence, approximately 8 g of the organic material in the crucible was lost.

Comparative Example 1 Using the conventional film manufacturing apparatus shown in Figure 5, a verificatory test was carried out into the controllability, the temperature rising process, and the stability of the film formation rate as in Example 1.

Glass substrates each having dimensions of 50 mm x 50 mm were arranged in rows by 3 columns in a substrate holder having a mounting region of dimensions 770 mm x 150 mm inside the vacuum chamber 50, which had an internal volume of 0.2 m3. The resistive heating boat 59, which had an opening part of dimensions 850 mm x 35 mm and a depth of 50mm, was positioned 150 mm from the surface of the glass substrates, and 1 OOg of Aiq3 was charged therein.

Next, the pressure in the vacuum chamber 50 was reduced down to 1 O-5 Pa, and the power source was turned on for the heater of the attachment-preventing plate 52, which was set to a target temperature of 400 C.

After the power source had been turned on and the temperature of each of the parts had stabilized, the power source was turned on for the heater of the resistive heating boat, which was set to a target temperature of 320OC, thus commencing film formation. The Aiq3 was thus heated, and approximately 5 hours was required for the rate of the film formation onto the substrates to reach 10 nm/sec. The amount of the Aiq3 lost from inside the boat from turning on the power source until the temperature of each of the parts stabilized was as much as approximately 20 g.

Example 2

Using the apparatus described in Example 1, film formation was carried out over 30 seconds such that the mean film thickness would be 300 nm, thus building up Aiq3 on the glass substrates.

After that, the film thickness of the organic thin film was measured for all of the glass substrates using a stylus type film thickness gauge. The result was that the film thickness variation index (the ratio of the thickness of the thinnest organic thin film to the thickness of the thickest organic thin film out of the 45 glass substrates) was 0.9 or more. From this result, it can be seen that according to the organic thin film manufacturing method of the present invention, thin films of uniform thickness with little fluctuation in the film thickness can be formed.

Furthermore, using the apparatus of the present invention, an investigation was carried out into the reproducibility of the film thickness upon carrying out film formation many times. Using the apparatus of Example 1, 30 seconds of Aiq3 film formation was carried out 50 times in succession, without replenishing the organic material in- between. The Aiq3 thin films obtained on the 50ih occasion exhibited a mean film thickness of 296 nm, and a film thickness variation index of 0. 9 or more, and hence the film thickness and the uniformity thereof were approximately the same as for the Alas thin films obtained on the l at occasion. From this result, it can be seen that according to the method of the present invention, even in the case that film formation is carried out repeatedly and hence the organic material in the crucible is consumed, high film thickness reproducibility is obtained.

Comparative Example 2 Using the apparatus described in Comparative Example 1, film formation was carried out over 30 seconds such that the mean film thickness would be 300 nm, thus building up Alq3 on the glass substrates. After that, the film thickness of each of the manufactured organic thin films was measured using a stylus type film thickness gauge. The result was that the film thickness variation index was not over 0.8, i.e. it was found that there were large fluctuations in the film thickness.

Upon separately providing a radiation thermometer in the vacuum chamber 50, and monitoring the temperature of the line source 51, it was found that fluctuations in temperature of approximately 5 to 1 0 C existed along the longitudinal direction of the line source 51, and that this was one factor in there being large fluctuations in the film thickness. Moreover, it is thought that unevenness in the introduction of the organic material 56 into the line source 51 (more specifically the resistive heating boat 59) also had an effect.

Furthermore, an investigation was also carried out into the reproducibility of the film thickness upon carrying out film formation many times. Using the apparatus of Comparative Example 1, 30 seconds of Aiq3 film formation was carried out 50 times in succession, without replenishing the organic material in-between. The Aiq3 thin films obtained on the 1 1 th occasion exhibited a mean film thickness of 360 nm and a film thickness variation index of 0.8, i.e. a film thickness approximately the same as that for the Aiq3 thin films obtained on the l st occasion could not be obtained. From this result, it can be seen that the film thickness reproducibility for the apparatus using the conventional evaporation source is poor.

Example 3

Using the film manufacturing apparatus of Example 1, trial manufacture of organic EL devices was carried out. Three of the film manufacturing apparatus of Example 1 were linked to a vacuum vessel for conveyance having a load lock, so that substrates could be moved between the film manufacturing apparatus without releasing the vacuum. Glass substrates (dimensions 50 mm x 50 mm) on each of which an ITO film had been formed to a thickness of 100 nm were mounted, arranged in 15 rows by 3 columns, on a substrate holder having a mounting region of dimensions 770 mm x 150 mm, and the substrate holder was conveyed into the vacuum vessel for conveyance from the load lock.

Next, the substrate holder was conveyed into the first film manufacturing apparatus, and an oc-NPD film of thickness 40 nm was deposited at a film formation rate of 2 nm/sec, thus forming a hole transport layer on each of the substrates. The substrate holder was then conveyed into the second film manufacturing apparatus, and an Aiq3 film of thickness 60 nm was deposited at a film formation rate of 2 nm/sec, thus forming an electrontransporting light-emitting layer on each of the substrates. Finally, the substrate holder was conveyed into the third film manufacturing apparatus, and an Ag-Mg alloy (Mg 90 mass%) film of thickness 100 nm was deposited at a film formation rate of 2 nm/sec, thus forming an electron- injecting cathode on each of the substrates, whereby organic EL devices were obtained.

A voltage of 20 V was applied to each of the 45 organic EL devices obtained, taking the ITO film as the anode and the Ag-Mg film as the cathode, and the current efficiency for the brightness was measured. The mean current efficiency for the 45 devices was 4 cd/A, and the variation in the current efficiency (the absolute value of the ratio of the maximum deviation from the mean current efficiency to the mean current efficiency) was within 10.

Comparative Example 3 Organic EL devices were manufactured as in Example 3, except that the apparatus of Comparative Example 1 was used as the film manufacturing apparatus.

Upon evaluating the 45 devices obtained, it was found that the mean current efficiency was approximately the same as in Example 3. However, it was found that the variation in the current efficiency was large at 20. It is thought that the fluctuation in the film thickness for the devices as described in Comparative Example 2 was a large factor in this variation arising.

As described above, according to the present invention, an organic thin film manufacturing apparatus and manufacturing method can be realized according to which: the filling of the organic material is carried out in a material introducing part that is independent to the vacuum chamber, and hence it is not necessary to open the vacuum chamber to the atmosphere during this filling; the material is fed into the vacuum chamber in a vapour state from the independent material introducing part, and hence the line source can be designed with no consideration being given to whether the material used is a subliming material or a material that evaporates after melting; it is not necessary to give consideration to the effects of changes in the evaporation plane of the material during manufacture; even if the apparatus is used many times during mass production, there is little fluctuation in the film thickness or the film formation rate; the efficiency of utilization of the organic material is high; control is easy, mass production is possible, and vapour deposition of an organic material onto large-area substrates is possible. The manufacturing apparatus and manufacturing method are particularly effective in the manufacture of large-area organic EL devices.

Claims

Claims 1. An organic thin film manufacturing method, characterised by

comprising a step of feeding an organic material in a vapour state into a line source of a vapour deposition apparatus that has said line source and is installed in a vacuum chamber from a material introducing part installed outside said vapour deposition apparatus, thus forming a thin film of said organic material on at least one substrate disposed inside said vapour deposition apparatus, wherein said material introducing part has a structure such that the pressure thereinside can be set independently of that inside said vapour deposition apparatus, and has an exhauster independent to that of said vapour deposition apparatus.
2. The organic thin film manufacturing method according to claim 1, characterised in that said material introducing part has a crucible for holding said organic material, crucible fixing means for holding said crucible, and heating means for heating said crucible, and said organic material is vaporized by heating said crucible using said heating means.
3. The organic thin film manufacturing method according to claim 1, 1 characterised in that said line source has a blocking plate for dispersing the vapour-state organic material that has been fed therein, and said blocking plate is temperature-regulated.
4. An organic thin film manufacturing apparatus, characterised by comprising: a vapour deposition apparatus that has a line source and is installed in a vacuum chamber; and a material introducing part that is installed outside said vapour deposition apparatus, has a structure such that the pressure thereinside can be set independently of that inside said vapour deposition apparatus, and is connected to an exhauster independent to that of said vapour deposition apparatus; wherein a vapour- state organic material is fed into said line source of said vapour deposition apparatus from said material introducing part, thus! forming a thin film of said organic material on at least one substrate disposed inside said vapour deposition apparatus.
5. The organic thin film manufacturing apparatus according to claim 4, characterised in that said material introducing part has a crucible for holding said organic material, crucible fixing means for holding said crucible, and heating means for heating said crucible.
6. The organic thin film manufacturing apparatus according to claim 4, characterised in that said line source has a blocking plate for dispersing the vapour-state organic material that has been fed therein, and said blocking plate is temperature-regulated.
7. An organic EL device manufacturing method, characterised by comprising the steps of: forming a first electrode on at least one substrate; forming an organic EL layer on said first electrode; and forming a second electrode on said organic EL layer; I wherein said step of forming an organic EL layer comprises feeding an organic material in a vapour state into a line source of a vapour deposition apparatus that has said line source and is installed in a vacuum chamber from a material introducing part installed outside said vapour deposition apparatus, thus forming a thin film of said organic material on said at least i one substrate which is disposed inside said vapour deposition apparatus, wherein said material introducing part has a structure such that the pressure thereinside can be set independently of that inside said vapour deposition apparatus, and has an exhauster independent to that of said vapour deposition apparatus.
8. The organic EL device manufacturing method according to claim 7, characterised in that said material introducing part has a crucible for holding said organic material, crucible fixing means for holding said crucible, and heating means for heating said crucible, and said organic material is vaporized by heating said crucible using said heating means. !
9. The organic EL device manufacturing method according to claim 7, characterised in that said line source has a blocking plate for dispersing the vapour-state organic material that has been fed therein, and said blocking plate is temperature-regulated.
10. An organic EL device manufacturing apparatus, characterised by comprising: means for forming a first electrode; means for forming an organic EL layer; and means for forming a second electrode; wherein said means for forming an organic EL layer comprises a vapour deposition apparatus that has a line source and is installed in a vacuum chamber, and a material introducing part that is installed outside said vapour deposition apparatus, has a structure such that the pressure thereinside can be set independently of that inside said vapour deposition apparatus, and is connected to an exhauster independent to that of said vapour deposition I apparatus; and wherein a vapour-state organic material is fed into said line source of said vapour deposition apparatus from said material introducing part, thus forming a thin film of said organic material on at least one substrate disposed inside said vapour deposition apparatus.
11. The organic EL device manufacturing apparatus according to claim 10, characterised in that said material introducing part has a crucible for holding said organic material, crucible fixing means for holding said crucible, and heating means for heating said crucible.
12. The organic EL device manufacturing apparatus according to claim I 10, characterised in that said line source has a blocking plate for dispersing the vapour-state organic material that has been fed therein, and said blocking plate is temperature-regulated.